Low-water alarm



H. B. T HURSTON. LOW WATER ALARM.

APPLICATLON FILED JUNE 29. 1920.

Patented Apr. 25, 1922.

- ATTORNEYS UNITED STATES .ATENT GFFICE.

LOW-WATER ALARM.

Specification of Letters Patent.

Patented Apr. 25, 1922.

Application filed June 29, 1920. Serial No. asaesz.

'1 '0 all whom it may concern:

Be it known that l, IIERMAN B. Tunas- TON a citizen of the United States, residing at iittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a certain new and useful Improvement in Low-\Vater Alarms, of which the following is a full, clear, and exact description, reference being bad to the accompanying drawings.

My inventionrelates to low water alarms of the type wherein a fusible member normally closes a steam pipe leading to an alarm signal, the fusible member under sufficient increase in temperature melting, and allowing the alarm to operate.

one of the objects of my invention is to provide, in a low water alarm ot' the type which is applied to the crown sheets of boilers, and operates to sound a whistle upon the water falling below a predetermined height, a positive closure for the steam line leading to the whistle, so that under no conditions, save that of excess temperature, may any steam escape.

A further object of the invention is to provide a socket member with a plug threaded thereto by tapering threads, the plug containing fusible material which is adapted to melt when the temperature reaches a certain point and thereby open communication through a steam line to a signal such as a whistle.

The invention is hereinafter more fully explained and its essential characteristics set out in the claims.

In the accompanying drawings wherein my invention is illustrated Fig. 1 is a side elevation partly broken away, showing a boiler equipped with my low water alarm; Fig. 2 is an elevation of the whistle showing parts in section; Fig. 3 is a central sectional view of the socket member and the plug; Fig. 4 is an elevation of the socket member; Fig. 5 is a cross section of the plug on the line 5-5 Fig. 4 looking in the direction of the arrows: Fig. 6 is an elevation of the plug: Fig. 7 is a section on line 7--7 Fig. 6 looking in the direction of the arrows.

Referring to the drawings, a boiler of any suitable type is indicated at 1. the crown sheet being shown at 5, a socket member is shown at 2 and is connected to a pipe 4. a whistle 6 being connected to said pipe as shown.

The whistle 6, (see Fig. 2) comprises a body portion 6, cut away as at 10 and provided with inclined threads 11, fitting similar threads on a coupling 12, the latter bemg fitted to the steam pipe 4. The exterior of the whistle may be provided with a wrench engagin portion 9 and the interior may be provide( with a shoulder 14 against which a plug 15 is shown as abutting. The plug 15 has a tight fit with the interior of the body portion 6 and may be cut away on a diagonal as shown at 16, and is provided with a passage 17, the latter serving as a passage for the steam or other fluid under pressure. As shown the duct 17 is offset. as regards the axis of the whistle, and pipe 4, and the chamber 18, provided by the cut away portion intercepts the axis of the pipe 4, as a result of this arrangement, when the fusible member to be later described melts. the steam blows the material composing said member upward through the pipe 4. After passing through the pipe the fusible material strikes the sloping wall 16 and is trapped in the chamber 18. The passage. 17 is thus kept clear and there is no possibility of the whistle failing to sound.

The socket member indicated generally at 2 may comprise a hollow bushing-like member shown as partially closed at one end by an inset portion 15. The exterior of the plug is shown as threaded at 18, adjacent the inset portion and also as having a series of channels 33 located above said threads and communicating with a chamber 20. The socket is shown having an extension 19, formed with a center passage 32. with which the recesses 33 may communicate. The pipe 4 may be threaded to'the extension 19 as shown. The plug containing a fusible material 34, is shown at 23, and may have the wrench engaging portion 25. said plug may be threaded at 26 to engage threads on the inset wall 15', of the socket. The plug may be provided near its upper end with a number of channels 27 arranged in any desired manner. but here shown as cruciform. and there may also be provided a passage such as 3.) leading from the end 36 of the plug in communication with the first mentioned channels 33. The portion 31 of the plug 23 may be ground to a cone to fit a simil \1' ground coned portion 30 on the extensio. 19 of the socket. The socket 2 and plug 23 may be made of brass. and the portions which form a conical closure at 30 and 31 being ground, a tight'complemented titis afforded when the plug 23 is screwed into lace, thereby Insuring a leak proot JUlllt.

he fusible material is placed in the plug 23, before the'latter is inserted in the socket. The plug 23 of the socket member may be removable at will.

To renew the fusible elements the plug 23 may be removed from the firebox without disturbing the connection between the socket member and the crown sheet or the pipe 4, and a new plug earr ing the fusible element readily inserted am screwed to position.

In operation when the water falls to a dangerous level, theincrease in heat will cause the fusible material 34 to flow. The molt/en material driven by the pressure of the steam is forced through the pipe 4 and enters the chamber 18 where it is trapped. The steam escapes through the passage 17 and sounds the whistle.

Having thus described my invention, I claim:

1. In combination with a boiler, a safety plug, a pipe and a whistle, said plug comprisin a tubular member havin fusible material therein, said whistle inc nding a body" part having a steam passage, a beveled face aligned with said passage and adapted to deflect the fusible material from the whistle, said beveled face extending throughout said passageway except for a small channel leading to the whistle dome and disaligned with the passage.

2. The combination with a conduit, a fusible block normally stopping admission to the conduit, a whistle connected to the conduit, said whistle carrying a plug having a beveled face occupying a space forming the projection of said conduit, whereby the fused material of the block thrown u ward by the steam will be deflected by said face, said plug having a narrow channel adjacent said face leading to the whistle dome.

3. The combination of a boiler, a conduit, a fusible block normally stopping admission to the conduit, a whistle having a bore of a larger size than said conduit, a coupling member joining said conduit and whistle and having an enlarged chamber, said whistle earrying a plug having a narrow channel formed therein and out of alignment with the conduit a beveled face adjacent said channel and occupying the pro jection of said conduit, whereby a trapping chamber is formed for preventing the carrying of fused material from the block into the whistle.

In testimony whereof, I hereunto afiix my signature.

HERMAN B. THURSTON. 

